Hoist



A aT-vm? April 25, 1961 H. F. MARTIN 2,981,289

HOIST Filed July 22, 1959 2 Sheets-Sheet l ia. Eff

April 25, 1961 H. F. vMARTIN 2,981,289

I-IOIST Filed July 22, 1959 2 Sheets-Sheet 2 INVENTOR.

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HIST

Henry F. Martin, Centerline, Mich., assignor to Detroit Hoist andMachine Co., Detroit, Mich., a corporation of Michigan Filed July 22,1959, Ser. No. 828,791

11 Claims. (Cl. 137-622) This invention relates to hoists, and moreparticularly to means for. controlling the movement and speed ofpneumatically actuated hoists or cranes by remote control.

It is an object of the invention to provide a novel and improved controlfor air operated hoists which may be easily operated with one hand andwhich permits the operator to position the hoist in an innite variety ofpositions and at various speeds, his other hand being free to handle theload.

It is another object to provide an improved motor control of this naturewhich is safe in operation and permits quick reversal of the directionof drive as well as prolonged driving in one direction withoutinconvenience to the operator.

lt is also an object to provide an improved hoist control of the abovecharacter which is of simple and foolproof construction, has relativelyfew moving parts and is economical to manufacture and easy to installand maintain.

Other objects, features, and advantages of the present invention willbecome apparent from the subsequent description, taken in conjunctionwith the accompanying drawings.

Figure l is an overall side elevational view of an air operated hoistincorporating the improved control of the present invention;

Figure 2 is an end elevational view of the hoist showing the relativepositions of the hoist and control;

Figure 3 is an enlarged view of the valve chest and push-button valves,parts being sectioned for clarity;

Figure 4 is au end elevational view partially in crosssection showingthe main valve construction, the parts being in closed position;

Figure 5 is a fragmentary view similar to Figure 4, showing one of themain valves on the verge of opening; and

Figure 6 is a view similar to Figures 4 and 5 showing the main valve inits fully opened position.

In general terms, the invention comprises a control for feeding air to apneumatically operated hoist motor which in the illustrated embodimentis of the vaned type. This control comprises a pair of main valvesmounted in a valve chest below the motor and connected to opposite sidesthereof. Each valve is movable between an exhaust position in which thecorresponding side of the motor is connected to exhaust, and a supplyposition in which compressed air is connected to that side of the motor.The main valves are controlled by a pair of pilot valves mounted in ahousing suspended below the main valve chest by such means as exible airconduits. These pilot valves are controlled by push-button levers andare so arranged that an operator may grip the pilot valve housing in onehand and .operate either of the push-button controls with his thumb.

Each pilot valve when depressed will supply pilot air pressure to oneside of the corresponding main valve at a rate in accordance with the'amount of depression on the push-button. An escape orice of adjustablesize is provided for each main valve operating chamber through PatentedApr. 25, 1961 which this pilot air may escape, the orifice being solocated that if pilot air is supplied at less than a predetermined ratethe main valve will move to the verge of but not sutciently to shift toits supply position. However, if the rate of pilot air supply isincreased, the main valve will be further moved so that air will besupplied to that side of the motor. The driving rate of the motor willbe determined by the amount of movement of the main valve which in turnmay be accurately controlled by the degree of movement of thepush-button pilot control. The other main valve will meanwhile be in itsexhaust position so that spent air may be exhausted after passingthrough the motor. Upon release of the pilot valve push-button, thepilot valve will be returned to its closed position, permitting the mainvalve to return to its exhaust position. Leakage means are provided inthe connection between the pilot and main valves to insure quick returnof the main valve so that a quick reversal of the hoist drive may beaccomplished.

Referring more particularly to the drawings, the hoist is generallyindicated at 11 and comprises wheels 12 mounted on a track 13 andsecured to a frame 14, a vane type of pneumatic hoist motor 15 beingcarried by frame 14 and driving a drum 16 carrying a cable 17 and a hook18 secured to the end of the cable. It will be understood that theprinciples of the invention could also be applied to other drivingarrangements such as those for crosstravel of the hoist.

A valve chest 19 is secured below motor 15, this chest being ofgenerally rectangular shape and having a compressed air supplyconnection 21 in the lower portion thereof. This supply connection leadsto an intake manifold 22 formed as a at chamber in the lower portion ofchest 19. A pair of vertically disposed tubular members 23 are disposedat opposite ends of manifold 22 and extend upwardly therefrom. Atransverse wall 24 is formed on the interior of each tubular members 23,thus dividing this member into a lower chamber 25 connected to manifold22 and an upper chamber 26. This upper chamber is connected by a sleeve27 to one side of vane motor 15,

so that the'two chambers 26 of tubular member 23 are internal bore ofeach valve is provided with an annular space 33. A pair of toroidalseals 34 and 35 are disposed at opposite ends of each space 33, theseals being urged to their inner positions by a helical compressionspring 36. The upper end of each spool valve 29 and 31 is relieved asindicated at 37, and a helical compression spring 38 is disposed betweenshoulder 39 of the valve and the bottom 40 of the air motor.

Each tube 23 is provided with a plurality of circumferentially spacedsupply ports 42 immediately below wall 24 and a plurality of workingports 43 immediately above wall 24. Portsr42 serve to connect chamber 25of each tube 23 with the corresponding chamber 33 of valve 29 or 31.Ports 43 serve to connect chamber 26 with an exhaust chamber 44 which isformed in the upper portion of chest 19 anduleads to an exhaust port 41in one side wall of the chest. The relative positions of ports 42 and 43with respect to the size of the chamber 33 is such that when valve 29 or31 is in its lower position as shownpin Figure 4, chamber 26 will beconnected to chamber 44 while chamber 25 is connected to chamber 33. Asvalve 29 or 31 slides upwardly, it will reach its .position asY shown inFigure 5 in which chamber 33 begins to be connected to ports 43, thelatter being cut off from chamber 44.

From there until the position of Figure 6 is reached, a graduallyincreasing supply of compressed air will be transmitted by annularchamber 33 from ports 42 to ports 43, so that motor 15 will be driven ata progressively faster rate.

In order to control the position of valves 29 and 31, each valve isprovided with a pilot valve, these being indicated at 45 and 46,respectively, in Figure 3. Pilot valves 45 and 46 are mounted in ahousing 47 wh-ich is suspended at an appropriate distance below chest 19by a supply line 48 for compressed air and pilot lines 49 leading fromvalves 45 and 46, respectively, to the undersides of their main valves.More specifically, supply line 48 is connected to inlet manifold 22 andextends downwardly from the centralV portion thereof, its lower endbeing connected by a coupling 51 to a vertical central passage S2 inpilot valve housing 47. A transverse passage 53 is connected at itsintermediate portion to the bottom of passage 52, and valves 45 and 46are engageable, with shouldered portions 54 at opposite ends of passage53. Enlarged passages 55 lead from the valves to vertical passages 56-which are in turn connected by couplings 57 to pilot lines 49. The upperends of pilot lines 49 are connected to chambers 58 formed in bores 28by the undersides of valves 29 and 31.

Valves 45 and 46 are formed at the ends of stems 59 which have enlargedthreaded portions 61 mounted in inserts 62, the ylatter being carriedwithin counterbores 63 of housing 47. The outer ends of shafts 59 carrypushbutton levers 64, and the central portion of housing 47 has adepending handle 65 disposed between the pushbuttons. The arrangement istherefore such that an operator gripping handle 65 with one hand mayengage either push-button 64 with his thumb. The push-buttons arenormally held in an inclined position with respect to handle 65, as seenin Figure 4, by torsion springs 66 connected between the push-buttonsand inserts 62, but may be depressed to their dot-dash line position asshown in Figure 4. When push-buttons 64 are in their solid lineposition, valves 45 and 46 will be closed, and rotation of shafts S9 bydepression of the push-buttons will gradually open these valves so thatcompressed air may be led from ycentral passage 52 to either passage 56.It is important to note that a leakage fit is provided in the areasmarked 67 as well as along threaded portions 61, so that any compressedair trapped in chambers 58, lines 49 or passages 56 when valves 45 and46 are closed will be permitted to escape.

A pair of restricted escape orifices 68 are provided in the side wall ofchest 19, these passages. leading from chambers S to the atmosphere. Thepurpose of escape orifices 68 is to control the movement of valves 29and 31 when pilot valves 45 and 46 are opened. For this purpose, theorifices are so located with respect to the bottoms -of their respectivechambers 58 that whenk the orifices are opened to their chambers, supplyports 42 will be on the verge of being connected to working ports 43.This is best seen in Figure 5. It will be noted that air will begin toescape from orifice 6.8 as valve 29 or 31 approaches a position in whichmotor will be supplied with air for driving purposes. In order tocontrol the rate of escape of air from orifices 68, each orifice isprovided with a restriction member, this being shown in the form of atapered screw 69 which is threadably supported by a bracket 71 securedto chest 19 and may be held in its adjusted position by llock nut 72.Each restriction member 69 may be adjusted so that when air is beingsupplied to chamber S8 at a relatively low rate, its corresponding valve29 or 31 may not move upwardly against the force of spring 38 asutlicient distance to supply motor 15 with driving air. However, whenair is supplied at a greater rate to chamber 58, it will build up inchamber 58 more rapidly than it can escape through orifice 68, therebymoving valve 29 or 31 upwardly. Motor 15 will thus be supplied with airfor driving purposes, and assuming that lil pilot valve 45 or 46 is heldconstant in its new position, valve 29 or 31 will arrive at a balancedposition since the increased pressure in chamber 58 will permit greaterescape through orifice 68. It should be observed that the presence ofadjustable restriction 69 will permit selection of the proper orificesize for a particular compressed air supply pressure, this pressurevarying in different localities and industrialV plants. The escape areasof orifices 68 will of course be substantially greater than those ofleakage lits 67, 61.

The operation of the air motor control may now be described. Assuming astarting position in which both valves 29 and 31 are in their exhaustposition, as shownin Figure 4, and both pilot valves 45 and 46 areclosed, pressure will be present in inlet manifolds 22 as well ascentral pilot housing passage 53 and at ports 42. Assuming that hook 18is in its upper position and that the left hand side of motor 15, asviewed in Figure 3, when supplied with air will cause hook 18 to belowered, lowerving of the hook may be accomplished by depressingpushbutton lever 64 connected to pilot valve 45. If only slow movementis desired, pilot valve 45 will be only partially opened and air will besupplied to the underside of main Valve 29, forcing the main valveupwardly until its orifice 68 is uncovered. Air will then begin toescape from chamber 58, but assuming that valve 45 is openedsuiiiciently, valve 29 will move slightly above the position shown inFigure 5 until slight portions of ports 43 are connected to chamber 33.Supply air will then ow from inlet manifold 22 to chamber 26 and fromthere to motor 15, causing the motor to rotate slowly so as to lowerhook 18. The exhaust air from the motor will pass through the otherchamber 26 and outwardly through ports 43 above valve 31, into exhaustchamber 44 from where it will be exhausted into the atmosphere. If it isdesired to lower the hook at a faster rate, push-button lever 64 will befurther moved, thus opening pilot valve 45 until main valve 29 has beenfurther raised as shown in Figure 6. When it is desired to stop themotor, pushbutton 64 will be released, so that spring 66 may close pilotvalve 45. Spring 38 will immediately return valve 49 to its exhaustposition, the air in chamber 58 escaping through orifice 68 and thenthrough the leakage path past area 6-7 and threads 61 as previouslydescribed. Ports 43 will thus be cut off from supply ports 42 andconnected to exhaust chamber 44.

Should it be desired to raise hook 18, pilot valve 46 may be opened in amanner similar to that described with respect to pilot valve 45. Itshould be observed that main valves 29 and 31 will be quickly returnedto their exhaust positions when their respective pilot valves areclosed, so that the reversal of motor 15 may be effected. It should alsobe noted that since in operation air will be blown through orifices 68and leakage paths 67 and 61, these flow paths will be continually keptclear of dirt or other obstructions. The realtively close, accurate andsensitive control afforded by the push-button and pilot valvearrangement together with the presence of orifices 68 has been found tobe escpecially desirable in cases where gradual changes in movement aredesired, such as in the lifting of sand molds.

While it will be apparent that the preferred embodiment of the inventiondisclosed is well calculated to fulfill the objects above stated, itwill be appreciated that the invention is susceptible to modification,variation and change without departing from the proper scope or fairmeaning of the subjoined claims.

What is claimed is:

1. In a pneumatic motor control a pair of main valves connected toopposite sides of said motor, each of said valves being movable betweena supply and an exhaust position, means urging each of said valves toits exhaust position, a pilot valve for each of said main valves, amanually grppable housing for said pilot valves, independently movableoperating elements for each of said pilot lul.

valves accessible to the hand of an operator gripping said housing, andmeans responsive to variable opening of either of said pilot valves forcausing its corresponding main valve to move to variable supplypositions, said lastmentioned means including a Irestricted orificeadjacent each of said main valves, each orifice being connectable to theoutlet of its corresponding pilot valve in response to movement of themain valve to a position immediately adjacent its supply position.

2. In a system for controlling a variable speed reversible air motor, ahousing below said motor, a pair of main valves slidably mounted in saidhousing, a supply port in said housing for each of said main valves, aworking port in said housing for each of said main valves, said workingports being connected to opposite sides of said motor, an exhaustchamber in said housing, each of said main valves being slidable in acontinuous manner between an exhaust position in which its working portis connected to said exhaust chamber and a supply position in which theow areas of said supply port and working port are connected to eachother, means urging said main valves toward their exhaust positions, apilot valve housing suspended below said main valve housing and adaptedto be gripped by the hand of an operator, a pair of pilot valves carriedby said pilot valve housing and having independently operable controlmeans engageable by the hand of an operator gripping said pilot valvehousing, each of said pilot valves being movable between a closedposition and a variable open position, a pilot supply line leading fromsaid main valve housing to said pilot valve housing, a pair of conduitsleading from the outlets of said pilot valves to said main valves,whereby opening of either of said pilot valves will cause movement ofits main valve toward its supply position, and a restricted orificeadjacent each of said main valves and openable in response to movementof the main valve to a position immediately preceding the connectionbetween said supply and working ports.

3. In a system for controlling a variable speed reversible air motor, ahousing below said motor, a pair of main valves slidably mounted in saidhousing, a supply port in said housing for each of said main valves, aworking port in said housing for each of said main valves, said workingports being connected to opposite sides of said motor, an exhaustchamber in said housing, each of said main valves being slidable in acontinuous manner between an exhaust position in which its working portis connected to said exhaust chamber and a supply position in which theliow areas of said supply port and working port are connected to eachother, a pilot valve housing suspended below said main valve housing, ahand gripping portion on said pilot valve housing, a pair of rotatablymounted pilot valves coaxially disposed within said pilot valve housing,a pair of thumb-engageable members secured to said pilot valves anddisposed at opposite sides of said hand gripping portion, means foropening each of said pilot valves a variable distance in response todepression of its corresponding thumb-engageable member, means urgingsaid pilot valves toward their closed position, a pilot supply lineleading to said pilot valve housing, a pair of conduits leading from theoutlets of said pilot valves to said main valves, whereby opening ofeither said pilot valves will cause movement of its main valve towardsits supply position, and a restricted orifice adjacent each of said mainvalves and openable in response to movement of the said main valvestoward its supply position.

4. In a system for controlling a variable speed reversible air motor, ahousing below said motor, a pair of main valves slidably mounted in saidhousing, a supply port in said housing for each of said main valves, aworking port in said housing for each of said main valves, said workingports being connected to opposite sides of said motor, an exhaustchamber in said housing, each of said main valves being slidable betweenan exhaust 6 position in which its working port is connected to saidexhaust chamber and a full supply position in which the flow areas ofsaid supply port and working port are connected to each other, a pilotvalve housing adapted to be gripped by the hand of an operator, aflexible pilot pressure supply conduit and a pair of flexible pilotvalve outlet conduits extending between said housings and serving tosuspend said pilot valve housing below the main valve housing, a pair ofpilot valves carried by said pilot valve housing and havingindependently operable control means engageable by the hand of anoperator gripping said pilot valve housing, each of said pilot valvesbeing movable between a closed position and a variable open position,and means Iresponsive to the position of i each main valve for causinggraduated movement of each main valve toward its full supply positionproportional to opening movement of its corresponding pilot valve.

5. In a system for controlling a variable speed reversible air motor, ahousing below said motor, a pair of main valves slidably mounted in saidhousing and forming valve actuating chambers therewith, a supply port insaid housing for each of said main valves, a working port in saidhousing for each of said main valves, said working ports being connectedto opposite sides of said motor, an exhaust chamber in said housing,each of said main valves being slidable between an exhaust position inwhich the working port is connected to said exhaust chamber and a supplyposition in which the ow areas of said supply port and working port areconnected to each other, a pilot valve housing suspended below said mainvalve housing and adapted to be gripped by the hand of an operator, apair of pilot valves carried by said pilot valve housing and havingindependently operable control means, each of said pilot valves beingmovable between a closed position and a variable open posi tion, a pilotsupply line leading to said pilot valve housing, a pair of conduitsleading from the outlets of said pilot valves to said main valves,whereby opening of either of said pilot valves will cause movement ofits main valve towards its supply position, a restricted orificeadjacent each of said main valves and openable in response to partialmovement of its corresponding main valve toward its supply position, anda leakage connection of smaller size than said orifice between each ofsaid main valve actuating chambers and the atmosphere whereby said mainvalves may be returned to their exhaust position.

6. The combination according to claim 5, said pilot valves having loosethreaded mountings comprising said leakage connections.

7. In a system for controlling a variable speed reversible air motor, amain valve housing below said l motor, a supply inlet chamber formed inthe lower porytion of said housing, an exhaust chamber in the upperportion of said housing, a pair of tubular members extending upwardly inspaced parallel relation from said chamber, an intermediate wall in eachof said tubular members, a main valve slidable on each of said tubularmembers, a supply port in each tubular member below said intermediatewall, a working port in each tubular member above said intermediatewall, an annular chamber formed in each of said main valves, each mainvalve being movable between an exhaust position in which said workingport is connected to said exhaust chamber and a full supply position inwhich the ow areas of said supply and working ports are connected tosaid annular chamber, a pilot va-lve housing below said main valvehousing, a pair of pilot valves carried by said pilot valve housing andhaving independently operable control means, each of said pilot valvesbeing movable between a closed position and a variable open position,and means respons-ive to the position of each main valve for causinggraduated movement of each main valve toward its full supply positionproportioned to opening movement of its corresponding pilot valve.

8. The combination according to claim 7, said lastmentioned meansincluding a main valve` oper-ating chamber formed on one side, of eachLof said main valves and connected to its corresponding pilot valveoutlet, and a restricted orice extending `from Ithe atmosphere throughsaid main valve housing to each of said operating chambers, each oricebeing so positioned as to be connected to its corresponding pilot valveoutlet conduit whenl the corresponding main valve is on the Verge ofconnecting said supply and working ports.

9. The combination according to claim 8, further provided With means foradjusting the size of each restricted orifice.

10. The combination according to claim 8, further provided With anatmosphere leakage connection for the bottom of each operating chamberof smaller size than said restricted orifices.

A11. In a pneumatic motor control, a pair of main valves connected toopposite sides of said motor, each of said valves being movable betweena supply and au 'exhaust position, means urging each of said lvalves toits exhaust position, a pilot valve for each of said main valves, andmeans responsive to variable opening of either of said pilot valves forcausing its corresponding main valve to move to variable supplypositions, said last-mentioned means Aincluding 4a restricted orificeconnected to atmosphere adjacent each of said main valves, each oricebeing connectable to the outlet of its corresponding pilot valve anamount proportional to movement of the main valve toward a positionimmediately adjacent its supply position.

References Cited in the tile of this patent UNITED STATES PATENTS2,743,708 Lungerhausen May- 1, 17956 2,831,554 Reynolds Apr. 22, 1958

